Chapter 12

gif and jpg file formats are used to store images.

(a) Give one reason for using each of the file formats. Each of your reasons must be different.

gif Used to store animated/moving images

Used to store icons/simple logos

jpg Used to store photographic images

Used to store graphics with complex colours and gradients

(b) Explain the differences between the two file formats.

gif

• Graphics Interchange Format

• Supported by all web browsers

• Can be animated images

• Supports 8-bit colours/256 colours/limited

• Features background transparency

• Image quality never degrades with resaves

jpg

• Joint Photographic (Experts) Group

• Supports 24-bit colours/16.7 million colours//More colours

• Image quality degrades slightly when a JPG is resaved

• Uses lossy compression

• No background transparency

• Enlarging the image can cause pixelation

• Image quality is better

(c) The file size of an image can be reduced by changing the file format of the image. State two other ways of reducing the file size of an image.

1 Change the resolution/quality of the image

2 Reduce the colour/bit depth

—> Change the compression method/Compress the file, Reduce layers

A web page can contain images saved as png or gif file types.

(a) State what is meant by png and gif file types.

png

• Raster/full colour digital photos

• Images with a transparent background

gif

• Moving/animated image

(b) Explain the differences between the two file types.

• Same images saved as a GIF loads/reads faster than PNG

• GIF uses limited colours (256) whereas PNG uses a bitmap of colours

• GIF can have moving and static images whereas PNG only have static images

• PNG can have transparent background

• PNG is compressed

• PNG is lossless

The student has placed images in the document. State two file formats she could have used for the images.

• Png

• Gif

• Jpg/Jpeg

• Bmp

• PDF

• IMG

An image has been changed in a number of different ways.

Original image For each of the following images describe the software editing technique used in order to produce the edited images shown from the original image. Edited images

A - Resize the image maintaining aspect ratio

B - Rotate the image 90 degrees anti clockwise/counter clockwise//270 degrees clockwise

C - Reflect the image in the Y axis

D - Brightness adjusted

The director of a zoo is writing a document about wallabies. He has taken an image of some wallabies (Fig. 12.1) and is planning the layout of the pages which will include part of the image. The image he plans to use is shown in Fig. 12.2

Name the editing technique that was used to change Fig. 12.1 to Fig. 12.2.

Cropping/crop/cut

Name other sources of digital images apart from using a digital camera.

• Internet

• Scanned images

• Images stored on: Smartphone/Mobile phone/PC/Tablet/SD card/Smartwatch

• Clipart libraries

• Screenshot

Tick (✓) whether the following statements about generic image files refer to jpg, png or gif file types.